Process for improving retention of fillers in fibrous material



United States Patent PROCESS FOR IMPROVING RETENTION OF FILLERS IN FIBROUS MATERIAL John Gwynant Evans, Menston-in-Wharfedale, James Harry Leach, Morley, Leeds, and William Salkeld Meals, Bradford, England No Drawing. Application March 13, 1951, Serial No. 215,378

Claims priority, application Great Britain March 21, 1950 11 Claims. (Cl. 117-121) This invention relates to the retention of water-sensitive hydrophilic, nonfibrous polymeric, organic fillers in or on fibrous materials. The invention especially concerns textile fabrics but it is also applicable to various other forms of fibrous materials including paper and yarns and even the fibres themselves.

The invention is especially useful when the fibrous material is made of fibres of natural, regenerated or modified cellulose, e. g. cellulose esters or ethers. The fibres may however be of silk or wool. is applicable to all natural or manufactured fibres and materials made therefrom.

Textile fabrics are frequently filled by impregnation with aqueous solutions or dispersions of hydrophilic polymeric substances, natural and synthetic, e. g. natural carbohydrates such as starches, gums or alginates; modified celluloses such as water soluble cellulose ethers; proteins, such as albumen, casein or zein; and synthetic polymers such as polyvinyl alcohols, partially hydrolysed polyvinyl acetates, and polyacrylic acid and its water soluble salts. All these hydrophilic, nonfibrous polymeric, organic fillers are naturally Water sensitive and on washing may be removed from the fibre so that the filled effect is reduced or even completely destroyed. It is the object of the present invention substantially to overcome such a disadvantage and to provide a process whereby such hydrophilic, nonfibrous polymeric, organic fillers are retained in the fabric.

It is known to use isocyanates and isothiocyanates (hereinafter, except in the specific examples, included in the term isocyanates) as fixing agents to render such hydrophilic, nonfibrous polymeric, organic fillers in fibrous materials resistant to washing.

A disadvantage with the use of isocyanates is that many of them are volatile during drying and heating and their fumes have, in a number of cases, pronounced physiological efiects. They are, moreover, insoluble in water.

The reaction products of bisulphites with monoor poly-functional isocyanates and isothiocyanates (hereinafter termed isocyanate-bisulphite reaction products) do not possess these disadvantages since they are water soluble and give rise to no fumes. We have found quite surprisingly that they may be used to produce similar effects to those produced by isocyanates themselves and with greater efficiency in view of their more suitable properties.

This is all the more unexpected since we have evidence that the nature of the reaction when the isocyanate-bisulphite reaction products are applied to cellulose materials and heated is different from the reaction of the corresponding isocyanates. This evidence is set forth in our co-pending application Serial No. 213,692 relating to the modification of properties of cellulosic materials by the application of these isocyanate-bisulphite reaction products.

The process according to the present invention is therefore characterised in that there is incorporated in the fibrous material, before, during or after the introduc- In fact the invention 2,710,816 Patented June 14, 1955 ICC tion of a water-sensitive hydrophilic, nonfibrous, polymeric, organic filler, an isocyanate-bisulphite reaction product, the material being thereafter submitted to heat.

Generally, water-sensitive hydrophilic, nonfibrous, polymeric, organic fillers contain reactive groups, e. g. hydroxyl, carboxyl, and/or amino groups, which we believe to be reacted with the isocyanate-bisulphite reaction product and thereby rendered insensitive to water.

In carrying out the process, the said reaction product and the hydrophilic, nonfibrous, polymeric, organic filler may be first applied to the fibrous material in the same or difierent aqueous solution or dispersion, the material being then dried and heated to an elevated temperature.

The optimum temperature for the heat treatment is the decomposition temperature of the isocyanate-bisulphite reaction product used. The heat treatment will normally be of 3-15 minutes duration at a temperature of C. to 200 C. but if a lower temperature is used the time necessary will be substantially greater. It will also be possible in some cases to carry out drying and heating simultaneously.

The heat treatment may be carried out by any of the conventional methods, but preferably is effected between C. and 180 C. for a few minutes in stenters or hot air chambers or through machines which use infra-red radiation as the source of heat. Alternatively, this heat treatment may be effected by passing the material through a bath of molten metal, e. g. containing low temperature melting alloys, or less preferably may be effected by treating the material with steam.

Although mono-functional isocyanates may be used to react with the bisulphite, it is preferable to use polyfunctional isocyanates such as a dior tri-isocyanate. In the case of the aromatic isocyanates, the tri-functional are preferred to the di-functional, whilst, in the case of the aliphatic isocyanates, it is preferred to use the difunctional having an aliphatic chain of not more than 10 carbon atoms. If mono-functional isocyanates are to be used, they should be either aromatic isocyanates or aliphatic isocyanates with a chain containing not more than 8 carbon atoms.

Specific examples of suitable isocyanate-bisulphite reaction products are the bisulphite reaction products of phenyl isocyanate, hexamethylene di-isocyanate, rn-

* toluylene di-isocyanate, m-phenylene di-isocyanate, the

mixture of poly-isocyanates marketed by I. C. I. Limited in xylene solution under the registered trade-mark Vulcafor V. C. C., and any of the corresponding isothiocyanates, and also allyl isothiocyanate. Further examples include the bisulphite reaction products of toluene 2:4 di-isocyanate, toluene 2:4:6 tri-isocyanate, mixtures of toluene 2:4 and 2:6 di-isocyanates and methylene bisp-phenylene isocyanate.

One method of making the isocyanate-bisulphite reaction product is to disperse the isocyanate in a saturated aqueous solution of an alkali metal bisulphite, e. g. sodium bisulphite, from which after a short time the isocyanatebisulphite reaction product Will separate out. Liquid isocyanates may be stirred into the saturated bisulphite solution but solid isocyanates should first be dissolved in an organic solvent such as benzene, toluene or xylene. The isocyanate-bisulphite reaction products may be dried at relatively low temperatures to white odourless solids. They are soluble in water to give stable solutions in contradistinction to the corresponding isocyanates which are decomposed by water. The sodium salts of the isocyanatebisulphite reaction products are generally soluble in water, but the corresponding potassium salts are not so readily soluble in water. Where the solubility of salts is low, they can be used in an aqueous dispersion. Conditions of use which lead to the hydrolysis of the reaction products, e. g. heating of aqueous solutions, should be avoided.

Alternatively to, but less preferably than, the introduc tion of the isocyanate-bisulphite reaction product as such to the material. this product can be produced in situ either by first applying the isocyanate and then the bisulphite, or vice versa. Thus the isocyanate may be applied to a fabric from a solution in an organic solvent which is then evaporated whereafter the bisulphite is applied from aqueous solution. Similarly the bisulphite can be applied to the fabric first from an aqueous solution followed by drying and the application of isocyanate from an organic solvent solution.

Alternatively, an emulsion of an isocyanate in a dilute aqueous bisulphite solution may be applied to the fabric.

In any of these methods for forming the isocyanatebisulphite reaction product in situ, the hydrophilic, nonfibrous, polymeric, organic filler may be applied to the fabric before, during or after the formation of the said reaction product. For example, the hydrophilic, nonfibrous, polymeric, organic filler may be introduced in any of the solutions or emulsions containing reagent.

In dilute solutions of bisulphites the reaction does not readily take place, but on drying and concentrating on the material the isocyanate-bisulphite reaction occurs.

it is a further advantage of this invention that as hydrophilic, nonfibrous, polymeric, organic fillers are frequently applied to fabrics or other fibrous materials before mechanical treatment in order to enhance the mechanical effect, increased resistance of both hydrophilic, nonfibrous, polymeric, organic filler and mechanical finish to water and washing can be simultaneously achieved, thus combining the present invention with that disclosed in our co-pending application Serial No. 213,691. Thus, for example, in fabrics which are to be glazed, starch is often applied to lay surface hairs and increase the glazed effect on calendering. On reacting with an isocyanatebisulphite reaction product in the manner described, both the filled effect due to the starch and the glazed effect are rendered faster to washing. In this case the mechanical finish must be applied to the fabric containing hydrophilic, nonfibrous, polymeric, organic filler and bisulphite compound before the heat treatment already described. The mechanical finish may comprise a heat treatment which brings about fixation of the hydrophilic, nonfibrous, polymeric, organic filler and mechanical effect or it may be followed by a heat treatment as already described.

It is also usual, especially when preparing finishes for such articles as Window hollands or book cloths, to weight the fabric with insoluble inorganic inert textile weighting agents such as China clay or barytes added to the hydrophilic, nonfibrous, polymeric, organic filler. These insoluble inorganic inert textile weighting agents are also removable by washing and by rubbing in the wet state and are much more firmly held when the polymeric filling agent which accompanies them has been fixed by the process according to the present invention.

Substances c. g. inorganic pigments such as titanium dioxide, lithopone or China clay are also frequently applied to lustrous fibres yarns and fabrics to impart a delustring effect. They are normally removable by washing but if applied with the hydrophilic, nonfibrous, polymeric, organic fillers mentioned herein and the isocyanatebisulphite reaction products applied as described then the delustred effect becomes remarkably resistant to Washmg.

The invention may be used to apply to a fibrous material a dye which either will not dye the material or will be removed therefrom by washing but which shows afiinity for a water-sensitive hydrophilic, nonfibrous, polymeric, organic filler. The hydrophilic, nonfibrous, polymeric, organic filler in this case may be used as a mordant. For example, such a dye may be applied to a fib material filled and treated according to the invention and, by virtue of the retention of the hydrophilic, nonfibrous, polymeric, organic filler due to the inventive treatment, is rendered fast to washing.

We have found that the heat treatment may advantageously be effected in the presence of an amide, an amidine or an amino triazine. In the case of a hydrophilic, nonfibrous, polymeric, organic filler such as starch such an addition is generally necessary in order to obtain the desired results. Preferably, a fabric or other fibrous material is impregnated with one of these compounds and with the hydrophilic, nonfibrous, polymeric, organic filler and the isocyanate-bisulphite reaction product from the same aqueous solution or dispersion, dried and then heated at an elevated temperature.

Suitable amides are urea, thiourea, acetamide, sulphonamide or p-toluene sulphonamide, and dicyandiamide; suitable amidines include guanidine and amino guanidine, and suitable amino triazines include melamine.

The improvement which is brought about by treatment with these amides, amidines or amino triazines is demonstrated by the increased retention of the hydrophilic, nonfibrous, polymeric, organic filler by the treated material, the firmer handle and the greater resistance to washing of any mechanical effect that may have been applied.

It will be clear that the treatment according to the present invention may be applied locally in a manner which will readily occur to a person versed in the art, e. g. by printing or stencilling, so as to obtain local or patterned effects.

Alternatively, the isocyanate-bisulphite reaction products may be applied all over the fabric but be rendered locally ineffective by the prior local application to the fabric of chemical resists, e. g. strongly alkaline pastes or be prevented from reaching certain portions of the fabric by the prior application of mechanical resists, e. g. waxes, to such portions. As a further alternative, discharge methods may be used, e. g. by applying the isocyanatebisulphite reaction product all over the fabric and then, prior to the heat treatment, applying a pattern of a strongly alkaline paste.

Fabrics or yarns treated by the method of the invention, whether mechanical finishes are applied or not, are more stable to dimensional changes during wetting or washing.

It is a further feature of the invention that the isocyanate-bisulphite reaction products may be mixed in the solid state with the polymeric hydrophilic, nonfibrous, polymeric, organic filler so that a composition of matter can be marketed in which hydrophilic, nonfibrous, polymeric, organic filler and fixing agent are advantageously mixed.

It has been found that the present invention may very suitably be used in conjunction with methods for forcibly altering the dimensions of a fabric.

For example, a well known method for producing a dimensionally adjusted woven fabric is to pass a fabric through a machine which forcibly reduces the dimensions of the fabric by pressing the yarns closer together, or, if

- so desired, which forcibly increases the dimensions of the fabric by pulling the yarns further apart. Such machines are described in British specifications No. 359,759 and No. 372,803.

The invention is applicable to materials that have already been finished in a conventional manner, that is to say the treatment may be applied for example to fabrics which contain softening agents, lubricating agents, antiseptics or which have been anticreased or stabilised by means of thermosetting resinous condensates.

The invention may also be applied by treating materials with the isocyanate-bisulphite reaction products before or simultaneously with conventional finishing agents.

The invention is illustrated, but not limited, by the following examples in which all parts and percentages are by weight:

Example 1 84 parts of hexamethylene di-isocyanate are added to 310 parts of a solution of sodium bisulphite in water containing 104 parts of sodium bisulphite. The two liquids are intimately mixed by means of vigorous agitation and as the reaction proceeds a white crystalline solid separates. The mix eventually becomes a stiff paste, from which the isocyanate-bisulphite reaction product can be obtained by filtration and washing followed by drying at 5060 C.

A plain cotton fabric is padded in a dispersion containing 2 parts of egg albumen and 5 parts of the bisulphite reaction product of hexamethylene di-isocyanate (as prepared above) in 93 parts of water. After mangling, the fabric is dried and subjected to a heat treatment for minutes at 150 C.

The firm handle so obtained is resistant to repeated washing.

Example II A plain cotton fabric is impregnated in a dispersion containing 2 parts of a partially hydroysed polyvinyl acetate and 6 parts of the bisulphite reaction product of hexamethylene di-isocyanate in 92 parts of water. The fabric is partially dried so that it retains 15% of moisture. It is then glazed by repeated passage between a smooth steel cylinder heated to 180 C. and a compressed paper bowl whereby a very firm handle and glaze are imparted to the fabric which are resistant to repeated laundering.

Example 111 A plain cotton fabric is impregnated in a dispersion containing 2 parts of corn starch in 88 parts of water to which has been added 5 parts of the bisulphite reaction product of hexamethylene di-isocyanate prepared as in Example 1 and 5 parts of urea. The fabric is then dried and heated to 150 C. for 10 minutes. The firm handle imparted to the cloth by the starch is resistant to laundering treatments and wetting.

Example IV The potassium bisulphite reaction product of phenyl isocyanate is prepared by stirring 121 parts of phenyl isocyanate and 350 parts of sodium bisulphite together at 5 C. for 2 hours. At the end of this time, the mixture has set to a white crystalline mass, which is dissolved by addition of 300 parts of water at C.

The solution is filtered warm and the filtrate is cooled to 5 C. At this temperature crystals of diphenyl urea are precipitated, and filtered off. Potassium chloride is then added to the solution when the potassium salt of the bisulphite addition compound of phenyl isocyanate is precipitated. This compound is of low solubility in water but may be used as an aqueous dispersion thus:

A plain cotton fabric is back filled with a dispersion containing 5 parts of the potassium bisulphite compound prepared as above in 95 parts of a dispersion of methyl cellulose which contains 3 parts of actual methyl cellulose. The fabric is then dried at C., and heated at 150 C. for 10 minutes.

The firm finish imparted to the fabric in this manner is fast to repeated washing.

Example V A bright filament viscose rayon fabric is impregnated in an aqueous dispersion containing 0.25 part of methyl cellulose, 2.5 parts of China clay and 10 parts of the reaction product of sodium bisulfite compound with hexamethylene di-isocyanate, prepared as in Example 1, in 87.25 parts of water. The fabric is dried and then heated at 145 C. for 10 minutes. The delustred finish imparted by the China clay is thus rendered resistant to repeated washing.

Example VI A warp twill fabric composed of viscose rayon staple fibre is impregnated in a dispersion containing 1 part of a partially hydrolysed polyvinyl acetate, 10 parts of the reaction product of sodium bisulphite with hexamethylene (ii-isocyanate and 5 parts of urea in parts of water.

Warp Weft shrinkage shrinkage 1. Fabric impregnated in partially hydrolysed Percen Percent polyvinyl acetate only 14. 0 2. 2. As 12, compressively shrunk according to B. P.

5. 7 1.5 3. Fabric impregnated in partially hydrolysed polyvinyl acetate, urea, and the reaction product of sodium bisulphite with hexamethylene di-isocyanate, compressively shrunk according to B. P. 372,503, and heated 2.0 0. 5

Example VII A viscose rayon staple-fibre yarn is impregnated in a dispersion of 1.5 parts of methyl cellulose in a solution of 10 parts of the sodium bisulphite reaction product of hexamethylene di-isocyanate and 5 parts of urea in 83.5 parts of water. The yarn is dried and heated at 145 C. for 10 minutes.

In this way the yarn is durably stiffened and will resist repeated soapings. If the yarn be deformed by crimping before heating to 145 C. then not only is durable stiifness imparted in baking but the crimp is durable too.

We claim:

1. Process for improving the retention in fibrous material of water-sensitive hydrophilic non-fibrous polymeric organic fillers comprising impregnating the fibrous material with a water-sensitive hydrophilic non-fibrous polymeric organic filler and an alkali-metal bisulfite addition product with a compound selected from the group consisting of monomeric aromatic and aliphatic mono to tri isocyanates and mono to tri isothiocyanates, the aromatic radicals, having monocyclic aryl hydrocarbon groups containing not more than seven carbon atoms and the aliphatic radicals having hydrocarbon group containing not more than ten carbon atoms, except in aliphatic monoisocyanates and isothiocyanates where the carbon chain has not more than eight carbon atoms, and thereafter submitting the impregnated fibrous material to heat at a temperature to decompose the isocyanatebisulfite addition product to fix the filler for retention on the fibrous material.

2. Process as claimed in claim 1 in which the heat treatment is for a period of 3-15 minutes at a temperature of 200 C.

3. Process as claimed in claim 1 in which the addi tion product is polyfunctional having from two to three isocyanate groups.

4. Process as claimed in claim 1 in which the aromatic addition products are trifunctional isocyanates and isothiocyanates and the aliphatic addition products are difunctional isocyanates and isothiocyanates.

5. Process as claimed in claim 1 in which impregnation includes an amide auxiliary compound selected from the group consisting of urea, thiourea, acetamide, dicyandiamide, p-toluene sulphonamide, guanidine, aminoguanidine and melamine.

6. Process as claimed in claim 1 in which impregnation includes an insoluble inorganic inert textile weighting agent.

7. Process as claimed in claim 1 in which impregnation includes an inorganic pigment.

8. Process as claimed in claim 1 in which the filler and addition product are introduced into the fibrous material in aqueous medium, and the material is then dried.

7 8 9. Process as claimed in claim 8 in which the drying 2,305,006 Holt et al Dec. 15, 1942 step and heat treatment are effected simultaneously. 2,376,908 Neiderhausern May 29, 1945 10. Process as claimed in claim 8 in which impregna- 2,430,479 Pratt et a1 Nov. 11, 1947 lion includes arr amide auxiliary compound selected from FOREIGN PATENTS the group consrstmg of urea, throurea, acetarmde, dlcy- 5 andiarnide, p-toluene sulphonamide, guanidine, amino- 81042 Great Bmam f1397 guanidine and melamine. OTHER REFERENCES clalhln. flbIOUS materlal resulting from the process of Petersen Annv der Chem. 562, pages 226429 10 Chemical Abstracts, vol. 44, pages 115 and 116, Janu- References Cited in the file of this patent 1950- UNITED STATES PATENTS 2,123,562 Ctaik July 12, 1938 

1. PROCESS FOR IMPROVING THE RETENTION IN FIBROUS MATERIAL OF WATER-SENSITIVE HYDROPHILIC NON-FIBROUS POLYMERIC ORGANIC FILLERS COMPRISING IMPREGNATING THE FIBROUS MATERIAL WITH A WATER-SENSITIVE HYDROPHILLIC NON-FIBROUS POLYMERIC ORGANIC FILLER AND AN ALKALI-METAL BISULFITE ADDITION PRODUCT WITH A COMPOUND SELECTED FROM THE GROUP CONSISTING OF MONOMERIC AROMATIC AND ALIPHATIC MONO TO TRI ISOCYANATES AND MONO TO TRI ISOTHIOCYANATES, THE AROMATIC RADICALS, HAVING MONOCYCLIC ARYL HYDROCARBON GROUPS CONTAINING NOT MORE THAN SEVEN CARBON ATOMS AND THE ALIPHATIC RADICALS HAVING HYDROCARBON GROUP CONTAINING NOT MORE THAN TEN CARBON ATOMS, EXCEPT IN ALIPHATIC MONOISOCYANATES AND ISOTHIOCYANATES WHERE THE CARBON CHAIN HAS NOT MORE THAN EIGHT CARBON ATOMS, AND THEREAFTER SUBMITTING THE IMPREGNATED FIBROUS MATERIAL TO HEAT AT A TEMPERATURE TO DECOMPOSE THE ISOCYANATEBISULFITE ADDITION PRODUCT TO FIX TH FILLER FOR RETENTION ON THE FIBROUS MATERIAL. 